Evaluation and detection of CCP antigen-specific T cells by ELISpot assay in patients with rheumatoid arthritis / 中华检验医学杂志

ABSTRACT

Objective To optimize and establish ELISpot assay for CCP/AST which could secrete IFN-γ and IL-4, and explore the role and clinical significance of CCP/AST cells in occurrence and development of RA disease. Methods CCP was used as specific-stimulator with FLAG peptide as a control,the frequencies of positive SFC which could specifically secrete IFN-γ and IL-4 in 64 cases of RA, 64 cases of non-RA autoinunune diseases and 30 cases of healthy individuals were tested by ELISpot technique. The diagnostic value of CCP/AST cells was evaluated in patients with RA disease. Meanwhile, the relationships among the indexes above and patient joint symptoms as well as other laboratory parameters were further analyzed and discussed. Results The results showed that the mediam numbers of IFN-γ-SFC and IL-4-SFC were 39(12-77)/3 x 105 PBMC and 1 (1-3)/3 × 105 PBMC in RA patients, the positive rates were 81.3% and 18. 8% respectively. The median value of IFN-γ-SFC/IL-4-SFC ratio was of 15(5-39), the positive rate was of 78. 1%. Both IFN-γ-SFC and ratio of IFN-γ-SFC/IL-4-SFC were significantly higher than those of non-RA diseases (Z = - 7. 458, - 7. 019, P < 0. 01 ) and healthy control ( Z = - 6. 643, - 5. 760, P <0. 01 ), also both these parameters in RA patients with positive anti-CCP antibody and negative anti-CCP antibody were significantly higher than those patients with systemic lupus erythematosns ( Z = - 6. 573, - 6. 098, - 4. 552, - 4. 726, P < 0. 01 ), ankylosing spondylitis ( Z = - 3. 520, - 3. 326, - 2. 950,-2. 126, P<0. 01 or 0. 05), other autoimmune diseases (Z = -4. 838, -4. 418, - 3. 681, -3. 839,P < 0. 01 ) and healthy controls ( Z = - 6. 553, - 5. 578, - 4. 635, - 4. 163, P < 0. 01 ). Combining IFN-γ-SFC, IL-4-SFC with IFN-γ-SFC/IL-4-SFC for RA diagnosis, the area under curve of receiver operating characteristic( ROCAUC) and Youden index were 0. 910 and 0. 747. The diagnostic sensitivity and specificity were 87. 5% and 87.2%. Positive and negative predictive values were 82. 4% and 91.1%, respectively. Correlation analysis showed that ratio of IFN-γ-SFC/IL-4-SFC was not only significantly correlated with antiCCP antibody(r =0.393, P <0.01), but also correlated with joint symptoms in patients such as with number of joints swelling-pain ( r = 0. 429 , P < 0. 01 ), number of joints damage ( r = 0. 463, P < 0. 01 ),rheumatoid factor (r = 0. 166, P < 0.01) and erythrocyte sedimentation rate (r=0. 199,P<0.05).Conclusions There is widely existence of CCP/AST cells activation and abnormity in RA patients,indicating higher frequency of CCP-specific Th1 cells. These results provides a new experimental evidence for an objective understanding the function of specific cellular immune responses and cytokine network regulation mediated by citrullinated proteins in RA. So, the assay for CCP/AST cells has potential values in RA diagnosis and clinical application.